Motors and Motor-Driving/Chapter 14

by Alfred Charles William Harmsworth

CHAPTER XIV

MOTOR CYCLES

By the Editor of 'The Motor-Car Journal'

To those who can realise, by actual possession, the pleasures of the motor-car, this chapter will be of little interest. But there are many aspiring motorists to whom the original cost of a car, or its maintenance when purchased, is a barrier to ownership. Hence the favour with which motor cycles are regarded, and the growing importance they are attaining in the automobile movement. The familiar forms are the tricycle, quadricycle, and the bicycle, the latter having rapidly come to the front, to the apparent supersession of the more cumbersome type of motor cycle. With regard to the permanent popularity of either form nothing need be said, individual preference being left to settle the question. But it may be pointed out that the bicycle is more conveniently adapted for storing where space is limited, and that it is to this kind of motor cycle that the attention of makers is being mostly directed at the present time.

There is no doubt that the motor cycle will prove an effective educational medium in connection with automobilism, for the intending motorist will be able to learn all about petrol engines at a much less cost than is demanded by the purchase of a motor-car. The experience thus gained will be extremely useful should the motor cyclist ultimately become the owner of a larger vehicle, while those who begin with motor cycles will probably enter the ranks of motor-car owners after they have realised the pleasures and delights of automobilism whether with the cheaper or the more expensive form. Thus the cycle will do much to popularise motoring.

For all practical purposes the motor cycle comes under the Light Locomotives Act of 1896 and the Local Government Board regulations by which its speed is restricted to twelve miles an hour. Restive horses and policemen must also be respected, and the motor cyclist must halt upon a signal from the driver of the former or the raising of the hand of the latter. Lights must be carried as on ordinary bicycles. In addition to observing these regulations, the owners of motor quadricycles, tricycles, or bicycles must take out licences at the cost of 2l. 2s. in the case of the quadricycle, and of 15s. in that of the others. Efficient brakes must also be provided.

Apart from machines now regarded as curiosities, the motor tricycle of MM. de Dion and Bouton was the most successful form of vehicle introduced after the adaptation of the internal combustion engine to road locomotion. The first made had a small 3/4-horse-power motor fixed to the rear axle, the carburetter being placed behind the main down tube to the frame. The size of the motor was gradually increased, until we now find tricycles in ordinary use with air-cooled motors of 23/4-horse-power capacity. Of a similar design was the Phoebus tricycle fitted with the Aster motor. It differed only in minor points from other machines, and in the use of copper radiating gills tightly fixed on the cylinder of the motor, the advantage of which (as Mr. Worby Beaumont remarks) is not very apparent. The Beeston tricycle was the first of the kind English- made throughout, but the Ariel motor tricycle was the first really successful English machine. It shows several variations in design from the original De Dion. Notably, the motor, instead of being placed to the rear of the back axle, is placed forward of it. A single case fills up the whole of the space in the main frame, and contains the battery, carburetter, and petrol tank. There are a few other motor tricycles, but their main features are on the lines of the above.

Passing to motor bicycles, they are of such recent development that they really have no history. Although Daimler designed a motor bicycle in 1885, it was not till five or six years ago that serious and sustained efforts were made to perfect the petrol motor bicycle. In this connection the Wulfmuller was a pioneer. It had a double-cylinder motor, driving the hind wheel, and was a cumbersome and unsuccessful machine. The Werner occupies a similar position among motor bicycles to the De Dion among motor tricycles. While gear driving has been universally adopted in the latter, most of the motor bicycles have been adapted for belt driving. One—that invented by Lieut.-Col. Holden—has dispensed with both, and has the novel feature of a four-cylindered engine, from which the motion is transmitted to cranks on the back wheel by means of connecting-rods. The Holden has another point of difference from the common practice in the fact that the cylinders of the engine are water-jacketed, while air-cooled motors are almost universally employed on motor bicycles.

The first point of interest in connection with motor bicycles is the position of the engine, and owing to the practice, in the early Werner machines, where the motor was fixed above the front wheel, it was long thought that the weight of the engine should be placed as high upon the bicycle as possible. That location, it was claimed, was necessary to ensure the stability of the machine, and to minimise the danger of side-slip. Experience, however, has shown that this is not so essential, and there are now a score or more of motor bicycles only two of which have the engine above the wheels. In the latest type of Werner the engine is placed halfway between the two wheels in a vertical position, thus bringing the centre of gravity very low. A low-down position between the wheels is being generally adopted, as tending to reduce the vibration and lessen the liability to side-slip.

The subject of side-slip is one of the greatest interest to all motor cyclists, and the position of the motor has been variously located, with a view of minimising its occurrence. It is generally acknowledged that motor bicycles are more prone to dangerous side-slips than are ordinary leg-propelled cycles. On a slippery road with the ordinary bicycle there is only the rider and the bicycle in question, but in the case of the motor bicycle the engine makes its presence felt, lessening that instantaneous and automatic control so essential for safety. The Minerva engine has been adopted on many bicycles. It is now of 11/2 h.-p.; the carburetter is a simple form of the surface type, and the petrol consumption stated to be about one pint for twelve to fourteen miles on level roads. The engine can also be lubricated without dismounting. In the Minerva motor bicycle the engine is fixed below the bottom tube of the frame slightly forward of the bottom bracket. The Excelsior was one of the first British motor bicycles in which the Minerva engine and system was adopted. Indeed, the extensive employment of the Minerva motor is one of the most astonishing features of the present development in motor bicycles. It is noteworthy, however, that several leading makers, while using the Minerva, have introduced in connection with it a number of special features which considerably facilitate the handling of the machine.

In the Quadrant motor cycle matters are simplified by one lever being made to control the switch, open and close the exhaust-valve, regulate the gas-supply, and vary the sparking. This reduction of the number of levers is undoubtedly a step in the right direction. The gas can be supplied in varying quantities, as usual, and is regulated by the lever from the lowest to the fullest supply before the advance of the sparking begins. Then when a greater speed is sought, it is obtained by the advance of the sparking, according to the pace desired, or in other words, the explosions are more rapid, the quantity of gas used being, of course, the full charge. In the ordinary arrangement it is possible to vary the supply of gas allowed to pass to the explosion chamber with the sparking lever at any point. Whether the restrictions imposed in this direction by the Quadrant device will prove to be a drawback has yet to be tested.

In the Phoenix motor bicycle, the Minerva engine is adopted with two or three ingenious additions. The switch is controlled from the handle-bar, the electrical contact being arranged near the engine. The switch lever is so arranged that when further moved the exhaust-valve is lifted. In the same bicycle, the space between the down diagonal and the rear wheel is used for a specially shaped tank for petrol, giving a total available supply sufficient for a run of 200 miles. The Enfield has its motor highly placed in front of the head of the frame and driving the rear wheel, the only combination of this position with rear driving that has been introduced. The Mitchell and the Thomas motor bicycles (which are of American design) have the motor above the bottom tube but close to the head. The Brown machine, which is of English design and construction, follows somewhat the practice of the last two named, but the motor is fixed lower down on the bottom tube. In the Shaw motor bicycle the motor is attached vertically in the rear frame, driving the rear wheel either by belt or chain as desired.

Power transmission, a subject already incidentally mentioned, is an important point with regard to motor bicycles.

Belt-driving was originally the only medium considered, as it overcomes much of the vibration, although the tendency to slip is an obvious disadvantage. The V section belt was selected for the early types, but in the Minerva motor bicycle a twisted belt is used, the slack in which can be taken up by increasing the twists. Even with this, however, there are disadvantages, and when riding in wet weather on sandy roads we have known it to grind the groove of the pulley-wheel, slipping of the belt naturally resulting. Although powdered resin may be a temporary cure for this, the best way is to untwist the belt and twist it in the reverse direction. In the new Werner flat belts with flat pulleys are used, and in the United States an endless raw-hide rope is adopted in some machines.

An innovation is made in the Singer motor bicycle in locating the whole of the mechanism in the driving wheel. The engine is placed vertically, and the Simms-Bosch magneto ignition is adopted. A modified surface type of carburetter is employed, and one small lever suffices to effect the whole of the control. In the Derby machine, a chain from the engine propels a friction roller bearing on the tyre, which is thus driven by frictional contact. It is claimed by the advocates of this system that no extra wear on the tyre results. Latterly, chains or cog-wheels have been experimented with, but machines with this kind of driving cannot as yet be said to have been thoroughly tested, and it remains to be seen whether chain or gear driving will obviate the drawbacks to the belt without introducing disadvantages of their own. Chains are employed in the Humber motor bicycle, a friction disc faced with leather being introduced to slip slightly when undue pressure falls on the chain. In this case the motor is an essential part of the frame, and forms the bottom tube.

No final judgment can be given on this question of transmission, for like everything else about motor bicycles, the whole subject is in a state of transition. But the difficulty is especially great when we find experts divided. There are two gentlemen of the name of Craig who have each devoted much attention to this subject. Mr. A. Craig of Putney tells us that he considers 'that in spite of slipping and breaking, belt transmission is the best. It is simplest and cheapest, and under good conditions an almost ideal drive.' He prefers a flat belt, of at least one inch width, and a jockey pulley on ball bearings. The jockey pulley is always abused because its purpose is misunderstood. It is not meant to jam the belt up tight, but to make it hug as much as possible of the circumference of the driving pulley. Twisted leather belts are in his opinion a nuisance. On the other hand, Mr. A. Craig of Coventry says, 'It has been a matter of surprise that the belt should have survived so long as a means of transmission in motor bicycles. Probably, the belt drive will eventually lose favour except for low-powered machines, and some form of chain or gear drive take its place.' Sir Roger de Coverley would probably have called this a case of 'much to be said on both sides,' and suggested that experience should determine the result.

Future developments in connection with motor bicycles will no doubt be concerned with spring frames and two-speed gears. Already some interesting work in these directions has been done, and in the latest types of Excelsior motor a spring head is employed which greatly reduces the vibration transmitted to the handle-bars. One drawback to the use of the motor bicycle in hilly districts is that the motor only gives out its full power when running at the normal speed. When going uphill the speed of the motor naturally slackens, and consequently the engine does not give off its standard capacity. To overcome this difficulty inventors are studying the matter from two different points of view. Some are in favour of the use of motors of higher capacity than those now in general use, while others are experimenting with two-speed gears, arguing that it is better to have a small engine kept steadily running, and so developing its full power notwithstanding the gradient, the low gear being used for hill climbing. The Chapelle, which is constructed on these lines, has already proved its capacity in several French races, and the Phœnix motor bicycle has just been introduced with a two-speed gear as a leading feature. Motor cycling, although hitherto enjoyed only by the male sex, is likely to prove attractive to ladies in the future, and already machines have been specially introduced for their benefit. The motor is placed below the bottom tube, and ample protection is afforded in the way of dress-guards, &c.

The novice need have no fear of his motor bicycle. It is not a haphazard aggregation of bits of metal, and although there arc bicycle motors composed of more than 140 separate pieces, they present no unfathomable mystery. But the mechanism requires understanding, and we advise the intending motor cyclist carefully to study the chapters on Petrol Engines, Ignition, &c., in this book. A clear understanding of these will conduce to the pleasure of early experiences, which otherwise may be more varied than delightful. Even then he will have much to learn before he can qualify for a police certificate as to his ability to attain a speed above the legal limit. Diplomas for obstruction can be more easily obtained in public thoroughfares, hence the advisability of early runs being taken in secluded districts.

Before setting out, the cycle should be carefully examined and the engine tried. It is necessary, too, to be assured that the tool-bag contains the requisite equipment of tools and spare parts. We can remember on one occasion a friend of ours had glanced over the mechanism of his cycle, and had made sure that everything was satisfactory. Removing the interrupter ' he retired to clean his hands after the operation. Returning to his bicycle, he exerted himself on the pedals, but no explosion occurred. Dismounting he again overhauled the machine, spent ten minutes or so in investigation, and was ultimately warned by a constable for creating an obstruction in the roadway. He tried everything except, let us hope, profanity, and was preparing to seek friendly aid, when, casually putting his hand in his pocket, he discovered the interrupter plug, and his troubles were quickly over. Many of the so-called failures of motor cycles are due to equally trivial causes.

There is nothing consistent about our English climate—except its variability; and the motor cycle must rise superior to changeable climatic conditions. During cold weather those riders whose machines are fitted with surface carburetters have often been troubled with regard to the 'mixture,' and even in the summer-time, when riding over very bumpy roads, the petrol in the carburetter will be thrown about, giving off more vapour than is required, and affecting the running of the motor. The only way to overcome this difficulty is by continually controlling the air inlet. A number of riders of the 1901 Werner got over the difficulty in winter by warming the carburetter by means of a branch from the exhaust-box, a flexible tube being used. It is not, however, an easy matter on this machine, the motor being on the head stem of the bicycle, and moving independently of the carburetter. Another plan is to procure some boiling water, and after soaking rags in it to wrap them round the carburetter till the petrol is warm enough to vaporise sufficiently. In many of the new designs of bicycles, however, spray-type automatic carburetters are being fitted. No doubt these have certain advantages over the surface type, but with their use the necessity of seeing that no dirt or foreign matter gets into the petrol tank becomes an urgent question. They should be placed as near as possible to a source of heat to prevent them from becoming frozen in cold weather.

In the majority of motor cycles electrical ignition of the jump spark type is adopted, although in a few cases the magneto arrangement is being employed. The escape of the electric current or the premature running down of the battery is one frequent cause of trouble where dry batteries or accumulators are used. It may result from loose electrical connections, bad contacts, and short circuits. If two of the terminals of the wires get connected with a film of moisture, a short circuit is the inevitable outcome: hence extreme care should be taken when riding for a considerable time in the rain. The rider should frequently test the accumulator with a voltmeter to see that the necessary charge is there, or if a dry battery is used, test the amperemeter, and he should always carry a spare battery. Then he should see that all contacts and connections are firmly made, and that every wire connection is covered and properly insulated. There may be trouble through the platinum points of the contact-breaker getting worn down or dirty with oil, or the platinum, on what is known as the 'trembler' (whether it trembles or not is a debatable point), becomes loose and causes jumpy progression of the machine. The remedies are obvious: clean the contact points or replace with a new 'trembler.' If the cautions here given are observed there should be freedom from electrical troubles between the battery and the sparking plug.

Sparking plugs are often a source of worry, but a friend has travelled 11,000 miles and only required three plugs. Apart from an absolute fracture of the porcelain, the main cause of stoppage is owing to the plug inside the cylinder becoming fouled with carbon through an imperfect mixture being used. Often too much lubricating oil is inserted in the crank-case. This then gets over, the top of the piston and is burnt up when an explosion takes place, leaving a heavy deposit of soot. When this occurs the plug should be removed and the points cleaned.

In long runs, when the motor becomes heated, the inlet valve-stem may stick on its seat through oil or the bye-products of the explosion getting on to the stems. A little petrol squirted by an ordinary bicycle oil-can on to the stem will generally overcome the difficulty. Another plan is to take out the inlet-valve and wash the stem with the finest black-lead and petrol. On evaporation the stem will be left well coated with black-lead, which is a very good lubricant where there is great heat.

In order that the motor should work well it is necessary to have good compression. In the four-cycle engine the charge is compressed every second stroke of the piston towards the head of the cylinder. To obtain good compression, which is the forcing of the mixture into a smaller area, there must be no leaks, and the cylinder, piston, and valves must be perfectly tight. Otherwise, when the mixture is reduced in volume it will leak out and there will be poor compression, with the result that the motor will not give anything like its proper power, the force of the explosion being greatly reduced. Such working, too, is not economical. It is necessary, therefore, to see that there are absolutely no leaks, and the points where leaking can occur are as follows:—(1) the inlet-valve; (2) at the sparking plug; (3) around the piston-rings; (4) at the exhaust-valve; (5) at the point between the explosion chamber and the cylinder-top, where the cylinder-head is fitted on to the cylinder. Every little leak, no matter how small, means a loss of power. The valves should be examined first, viz. the inlet and the exhaust. They should be packed with suitable washers, and it should be seen that they set firmly on their seats. If there is any wearing of the metal the valves should be ground until the surfaces are perfectly smooth, so that an absolutely tight joint is made on the seating. Sometimes the ignition plug is not properly screwed up, and this should be looked to; there should also be proper packing between the plug and the cylinder at the junction. One of the most important places to look for leaks is at the piston-rings. These are set in grooves on the side of the piston, and make it fit tightly in the cylinder. On account of the excessively high temperature inside the cylinder, which dries up the lubrication, the rings may not run well, and will allow power to be lost, particularly if the engine has been out of use for a time. A little paraffin dropped into the cylinder through the compression tap will ensure free and proper operation of the piston-rings. The petrol motor is a very economical producer of power, unless something like a leak or bad ignition is taking place, and while really simpler than a steam engine, it seems more difficult of comprehension to the budding motorist.

The owner of a motor cycle who expects to use it constantly without previous experience, and not run up against various sources of stoppage and breakage, will find himself mistaken. A frequent experience is to run the whole gamut of troubles, and thus by actual knowledge having learned to fix all the various parts, the operator is qualified to take care of his machine. These troubles occur for three principal reasons. First, the ordinary individual who buys a motor cycle will not make a careful study of the manner in which the machine is built and how it works, but prefers to tackle it on the 'hit and miss' plan and learn by hard knocks and experience. Second, carelessness and the disinclination many persons have to take proper care of a piece of machinery. A motor cycle, however, cannot be expected to run properly unless it receives regular attention. Third, from accidents pure and simple. As already explained, a great deal of trouble might be avoided if riders would only take the pains to understand the principle of the machine before attempting long journeys.